Water-cooled furnace door



Dec. ll, 1951 E. E. BROWN ETAL 2,577,736

wATER-CooLED FURNACE DOOR Filed July 15, 1946 1I "www" 4 llge3c INVENTORS Patented Dec. l1, 1951 WATER-COOLED FURNACE Doon kEly E. Brown and Emery Miller, Portsmouth,

Ohio, assignors to Blaw-Knox Company, Pittsburgh, Pa., `a corporation of New Jersey Application July 1s, 1946, serial No. 683,444

3 Claims.

This invention relates to Water-cooled furnace doors of the type used, for example, on openhearth furnaces in steel plants.

Open-hearth furnace doors are subject to in tense heat and to severe conditions of service. Doors in general use today are made of welded steel plate or plate and structural shapes, and comprise a hollow panel with hollow marginal rails or flanges of greater thickness than the panel. These rails form a recess on the inner side of the door to accommodate a refractory lining. Water-cooling is necessary to preserve the shape and integrity of the door. The refractory lining is necessary to prevent excessive absorption of heat from the furnace by the water-cooling. For many years it Was standard practice to line furnace doors With fire brick. The recess in the door usually has a depth of about 4 M2", corresponding to the Width of a brick. The lining has a surface area corresponding generally to the size of the opening in the furnace Wall and the dimensions of the lining accordingly are quite large in comparison with its thickness. For example, a lining may be 4 feet Wide by 3 feet high. In recent years, a refractory material which is plastic When applied and sets up When exposed to the air, has been used to line furnace doors and has been found to have a longer life than brick linings. The present invention is directed particularly to plastic-lined doors.

The lining of a furnace door must be securely held in place for several reasons: first, the thermal conditions are severe and are highly adverse to the stability of a refractory lining Within the marginal rails or flanges of the door; second, the door is usually slammed in raising or lowering it and is apt to receive heavy blows from the charging machine or otherwise; and third, the lining inevitably erodes or dissipates in service and becomes progressively thinner so that it must ultimately be replaced. Accordingly, it is necessary to provide means for retaining the lining such that it will not only be initially stable and adequate to withstand the severe conditions of service, but will be effectively supported" throughout the expected useful life of the lining material.

The most usual practice has been to dispose the inner Walls of the door rails or flanges at a slight angle to the panel, so as to provide a dovetail lit between the rails and the refractory filling. Additional anchoring means, however, have been found essential and various forms of anchors have been used. Such anchors .are

a 2 eventually exposed to the furnace heat by the erosion of the lining and, if not water-cooled, they are burned away and require replacement which involves considerable expense in time and labor.

The door-lining material applied in plastic form which has been used is a basic refractory having a length of life which is many times that Cil of brick lining. This advantage may be offset partially, at least, by the higher cost of the materials and the greater expense of installation according to prevailing practice. The life of a plastic-applied lining is affected by the manner of installation in the recess, i. e., the compactness and equality of distribution when placed, the character of the anchors, and the thoroughness of drying before the door is placed in service. Overall economy is determined by the cost of relining which includes the necessary preparation of the door and the replacement of the anchors if needed, as Well as the cost of the lining material and the labor of applying it. Attempts to patch or partly reline a door have not proved successful and completeremoval of all lining material remaining in the door is necessary before relining. Accordingly, it is an object of our invention .to provide a door which permits renewal of the lining at minimum expense.

The necessity for anchors to support the lining is occasioned by the tendency of the lining material to slump or flow under the high temperatures encountered. General experience has indicated that a plastic-applied lining must be divided up into relatively small areas, each With its own means of support, in order to maintain the integrity of the lining. Various forms of anchors for'providing support at close intervals have been used. The form which has been used mostextensively andl given the best results heretofore comprises short studs secured endwise to the inner face of the door panel and distributed in spaced relation over the area thereof. These studs, however, burn olf as erosion of the lining proceeds. Before a door can be relined, the remnants of the studs must be removed and new studs secured in place. This adds materially to the overall cost of the relining operation. In most cases, in fact, this is the largest item in the overall cost.

' vWe have invented a novel furnacedoor adapted to receive a lining of the plastic-applied type which is uninterrupted over an area corresponding substantially to the furnace opening, Which lining may be readily applied at low cost and preserves` its integrity Hover long periods under severe operating conditions. In a preferred ernbodiment, we provide a door comprising a hollow panel and hollow rails or anges extending therefrom, with elongated keying members such as pipe lengths extending vertically between the upper and lower flanges and communicating with the interior thereof. These pipe lengths are wholly embedded in the lining when it is applied.v They facilitate the drying of the lining after it is applied in plasticV form by providing passages through which steam may be forced to heat the interior of the lining. When the door is installed, the pipe lengths afford passages for circulating cooling water from the lower flange through the lining to the.. upper flange by thermo-Siphon action. The. third andY principal function of the pipe lengths istoanchor the lining in the recess and support it against slumping. not burn away and do not have to be replaced. Theyare spaced apart and thus afford easy access to the lining space and facilitate removal of the lining material remaining in place preparatory to relining.

A complete understanding of our invention may be obtained from the following detailed; description and explanation which refer to theY accompanying drawings illustrating a` preferred embodiment. In the drawings:

Figure 1 is an elevation looking on the` door from the inner face;

Figure 2 is a verticaly section taken along the plane of line I-Il of Figure l;

Figure 3 is a view partly. in plan and partly in horizontal section along. the plane of the line III-.III of Figure 1; and

Figure 4 is a horizontal section taken along the plane of line IV-IV of Figure 1.

Referring in detail to the drawings, a watercooled furnace door adapted to receive a lining of plastic refractory material comprises a hollow. panel IB having spaced outer andinner walls II. and I2. The panel is generally rectangular and hashollow rails orflanges along its edges, the upper and lower flanges being designated i3 and I4, respectively, and the side iangesy I5. These flanges dene a recess for a filling or lining of refractory material I5. A conical frustum Il of metal plate extends inwardly from the outer wall II` to provide a sight hole and a wa-l ter jacket I8 surrounds the frustum and communicates With the panel III and lower flange I4. Lifting lugs I9 are attachedto the upper flange I3 and inlet and outlet connections '20 and 2Il also communicate therewith. VThe construction described so far is conventional in theY art.

In our improved door construction, we provide water-cooled members 22 for anchoring the lining materials. These members are pipe lengths spacedl across the Width of the door and extending vertically between the upper and lower rails or flanges I3 and I4. The pipe lengths communi.- cate-with the interior of the flanges. Thevmiddle pipe length extends from the upper ange to the. water jacket I8. The pipe lengths 22 also communicate with the main bodyV of the panelV through intermediate passages defined by short pieces of pipe 2'3. Hence when the water space ofthe door is nlled, water ows into these vertical pipes from a plurality of separate inlets; and as the water is heated in the pipes embedded in the refractory, circulationupwardly; through the pipes occurs, the flow of water thereinto bie--l ing apportioned among these inletsas local tem- Since they are water-cooled, they do.

ing on. circulation of steam through the interior of the door,r beforeV rehanging it after relining.

The pipes 22 effectively anchor the lining in place in its recess. They are smaller in diameter than the depth of the recess and are spaced from .the inner and outer boundaries thereof. In

applying theV lining, the refractory material is rammed in behind the pipes and when it has set. into a monolithic mass, the lining is tightly 'keyed to the door.

The: pipe lengths 23 previously mentioned, which may be nattened pieces of pipe of suitable size welded in place, actas struts to tie the pipes 22 and the panel together as a rigid structure.

One of the steps, necessary in lining a door withplasticrefractory material isv the dryingl of the lining after it has been applied. As stated above, this is usually done by circulating steam through the hoilow interior of the door. This is usually continued for several hours. Our invention facilitates the, drying-out process because the pipes 22 and 23; carry the steam through the interior of the lining itself. Itis also necessaryto provide for the escape of moisture from the lining as the drying proceeds. This presents noprobiern on-theinner exposed face of the door. The usual practice is to punch small holes therein for the full depth of the material while it is plastic. To permit thel escape of moisture from the other face in contact with the door panel, we provide small pipe lengths 212 between the plates Il and I2; the platesv themselves having holes therein in alinement with the pipe lengths so as to provide continuous passages extending through the door body.

Although we have illustrated and described but a preferred embodiment of our invention, it will be understood that changes in the details of construction may be` made without departing from the spirit of the invention or the scope of the appended claims.

Weclaim:

l. In a water-cooled furnace door for an openhearth furnace or the like,` a hollow panel having a main body with innerand outer walls between which cooling water` isA adapted to be circulated in a substantially unrestricted manner, said hollow panel furthery having peripheral hollow iiangesextendinginwardly and defining with said inner wall a recess, adapted to be, filled with a plastic. refractoryY material, a plurality of substantially vertical keying pipe members within said recess4 and extending Vbeta-'een and connected at. theirV ends to the. upper and lower of said flanges, the interior of said keyingv pipe members opening into, the .interior ofv said flanges,l said keying pipev membersfurther being between and spaced from said inner wall and the plane defined; by thennermost edges of saidrecess, and a plurality of pipe` pieces extending between said keying pipe members and said` inner wall and interconnecting the interior ofV said main body of saidhollow panel andthe, interior of said keying pipe.E members respective lyA whereby a plastic refractory: material. may; be ris-,idly anchored in` said furnace door and the. temperature thereof appropriately affected by circulation of water through said hollow panel, keying pipe members and pipe pieces.

2. In a water-cooled furnace door for an openhearth furnace or the like, a hollow panel having inner and outer walls between which water is adapted to be circulated in a relatively random manner, said hollow panel further having an inward recess defined at least in part by said inner wall, said recess being adapted to be lled with a plastic refractory material, a, plurality of substantially vertical tubular keying members within said recess and spaced both from said inner wall and the plane of the inner edges of said recess, said keying members being` connectedyat both ends of each thereof to said hollow panel so that the interiors thereof respectively open into the interior of said hollow panel at spaced apart points, and a plurality of small' pipe lengths extending between and connected in sealed relation to said inner and cuter walls respectively to provide moisture escape passages directly between said recess and the outside of said hollow panel, whereby a plastic refractory lining substantially filling `said recess may be respectively anchored, dried and cooled.

3. In Aa water-cooled furnace door for an openhearth furnace or the like, a hollowpanel having inner and outer walls between which water is adapted to be circulated in a relatively random manner, said hollow panel further having peripheral hollow iiangesextending inwardly and dening with said inner wall a recess adapted to be filled with a plastic refractory material, a plurality of substantially vertical tubular keying members within said recess and spaced both from said inner wall and the plane of the inner edges of said recess, said keying members being connected at the respective ends of each thereof to the upper and lower of said anges so that the interiors thereof respectively open into the interior of said anges, a plurality of pipe struts extending between and respectively connected to said keying members and said inner wall, said pipe struts further interconnecting the interiors of said keying members and of said hollow panel at intermediate points along the respective lengths of said keying members, and a plurality of small pipe lengths extending between and connected in sealed relation to said inner and outer walls respectively to provide moisture escape passages directly between said recess and the outside of said hollow panel, whereby a rigid furnace door structureis provided in which a plastic refractory lining substantially filling the recess therein may be respectively anchored, dried and cooled.

ELY E. BROWN EMERY MILLER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Germany Feb. 21, 1930 

